And just how big is El Gordo thought to be? It "has mass about 2 quadrillion ... times that of the sun, making it 'the most massive known cluster in the distant universe.' "

El Gordo is about 7 billion light-years from us. Scientists hope its discovery will help shed some light, as Space.com says, on "dark energy" and "dark matter." And, as the BBC says, it's possible El Gordo will help us figure out how galaxy clusters "form, grow and collide with one another."

NASA adds that "galaxy clusters, the largest objects in the universe that are held together by gravity, form through the merger of smaller groups or sub-clusters of galaxies. Because the formation process depends on the amount of dark matter and dark energy in the universe, clusters can be used to study these mysterious phenomena."